Researchers report that when they exposed human leukemia cells to grape seed extract in test tubes, the leukemia cells died sooner than usual. And the grape seed extract didn't hurt normal cells.

"What everyone seeks is an agent that has an effect on cancer cells but leaves normal cells alone, and this shows that grape seed extract fits into this category," researcher Xianglin Shi, PhD, says in a news release.

But Shi says that although the grape seed extract research is "very promising," it's still in its early stages. "It is too early to say this is chemoprotective," Shi says.

In 2006, other scientists reported that grape seed extract showed promise against colon cancer in lab tests on mice. Shi's team also read reports from other researchers studying grape seed extract and leukemia.

Shi's team looked for clues about how grape seed extract hastens leukemia cell death. They found several proteins that the grape seed extract apparently affected. Those proteins could make "attractive targets," Shi and colleagues write in the Jan. 1, 2009, edition of Clinical Cancer Research.

Shi's study didn't include testing grape seed extract against leukemia in people or animals.

For now, the researchers aren't making any recommendations about grape seed extract for leukemia patients. But they write that their findings may have implications for adding grape seed extract or other agents to chemotherapy or other therapies for leukemia and perhaps also for other blood cancers.